KR20110010802A - Method for enlarging heat exchanger tube and device for enlarging heat exchanger tube - Google Patents

Abstract

When expanding a thin U-shaped heat exchange tube and forming a flare in the expanded opening, a buckling phenomenon is more likely to occur at the boundary between or near the straight tube portion and the hairpin portion of the heat exchange tube. The problem of the expansion method of a heat exchange tube is eliminated. The opening of the U-shaped heat exchange tube 56 passing through the fin layer 54 protrudes from the upper surface of the fin layer 54, and the hair fin portion 56b of the heat exchange tube 56 is lowered from the fin layer 54. The primary expansion pipe which protrudes from a surface, inserts the expansion billet 22 into each opening part of the heat exchange tube 56, expands each straight pipe part 56a of the heat exchange tube 56, and integrates it with the fin 50. The expansion tube billet 22 is inserted at or near the boundary between the straight pipe portion 56a and the hairpin portion 56b of the heat exchange tube 56, and the primary expansion is completed. The expansion billet 22 is held at the finished position, the flare punch 24 is inserted into the opening of the heat exchange tube 56 subjected to the primary expansion pipe, and the flare portion 60 is provided at the tip end of the heat exchange tube 56. To form.

Description

Expansion method of heat exchange tube and expansion device of heat exchange tube {METHOD FOR ENLARGING HEAT EXCHANGER TUBE AND DEVICE FOR ENLARGING HEAT EXCHANGER TUBE}

The present invention relates to a method for expanding a heat exchange tube and a device for expanding a heat exchange tube.

When manufacturing the heat exchanger used for an air conditioner etc., as shown in FIG. 5A, normally, the some collar hole 102 formed in each fin 100 of the fin layer 104 which laminated | stacked the several sheets of fin 100 was laminated | stacked. The U-shaped heat exchange tube 106 is inserted into each of them.

Since a gap exists between the inserted heat exchange tube 106 and the inner wall surface of the collar attachment hole 102, the expansion billet 108 shown in FIG. 5A is inserted into the heat exchange tube 106, and the heat exchange tube 106 is provided. Expand the straight pipe portion 106a of the first pipe to be integrated with the pin 100. At this time, the hair fin part 106b of the heat exchange tube 106 which protrudes from the lower end surface of the fin layer 104 is supported by the receiving part 116.

In addition, the distal end portion of the flare punch 110 shown in FIG. 5A is inserted into the distal end portion of the heat exchanging tube 106 subjected to the primary expansion pipe, and the distal end portion and the vicinity of the heat exchange tube 106 subjected to the primary expansion pipe are inserted. The diameter expansion part 112 is formed by further expanding a diameter and the flare part 114 is formed in the front-end | tip of the diameter expansion part 112 further.

In the diameter expansion part 112 and the flare part 114 formed in this way, as shown in FIG. 5B, the one end part of the curved connection part 120 connected with the adjacent U-shaped heat exchange tube 106 is connected. Is inserted.

As the expansion apparatus which expands into the heat exchange tube 106 shown in FIG. 5, the expansion apparatus 200 shown in FIG. 6 described in the following patent document 1 is known, for example. The rear end portions of the plurality of mandrels 202 and 202 are attached to the expansion pipe 200 shown in FIG. 6, and the press-fitting plate 206 is provided to be capable of lifting up and down by the cylinder devices 204 and 204 as drive means. And the flare stand 210 which is suspended below the flare stand 210 by the hanging members 208 and 208 on the press-fitting plate 206, and has descended with the press-fitting plate 206. In contact with the 210, the balancers 212 and 212 supporting the flare stand 210 at a predetermined position and the flare stand 210 are supported at the predetermined position by the balancers 212 and 212 are dropped. The contact table 216 provided at the predetermined position of the support body 214 extended upward from the flare stand 210 so that it may contact the indentation board 206 is provided.

The expansion billet 108 shown in FIG. 5A is attached to each distal end portion of the mandrel 202, 202, and the flare punch 110 shown in FIG. 5A is attached to the flare stand 210. As shown in FIG.

Patent Document 1: Japanese Patent Application Laid-Open No. 09-99333

(Summary of invention)

(Tasks to be solved by the invention)

According to the expansion apparatus 200 shown in FIG. 6, the U-shape which is provided below the flare stand 210 and inserted in the collar attachment hole 102 of each pin 100 which forms the pin layer 104 is formed. To the heat exchange tube 106, the press fitting plate 206 is dropped by the cylinder devices 204 and 204 to insert the expansion billet 108, and as shown in FIG. 7A, a straight pipe portion of the heat exchange tube 106 is shown. A primary expansion is performed to expand 106a and integrate it with the pin 102. At this time, the flare stand 210 is supported at the predetermined position by the balancers 212 and 212, and the front end of the flare punch 110 mounted to the flare stand 210 is primary, as shown in FIG. 5A. It is located in or near the opening of the heat exchanging tube 106 which expanded.

When each expansion pipe billet 108 reaches the predetermined position of the straight pipe part 106a of the heat exchange tube 106, as shown in FIG. 7A, the press fitting plate 206 abuts against the contact table 216, The flare stand 210 is pushed downward with greater force than the balancers 212 and 212 through the contact table 216 and the support 214. For this reason, the flare punch 110 and the expansion billet 108 are simultaneously pressed, and as shown in FIG. 7B, each expansion billet 108 pushes into the hairpin part 106b, and completes primary expansion. The flare punch 110 forms the diameter extension 112 and the flare 114 at the tip of the heat exchange tube 106.

According to the expansion apparatus 200 shown in FIG. 6, expansion can be performed smoothly with respect to the heat exchange tube 106 of comparatively large width.

By the way, in the heat exchanger used for air conditioners etc., in recent years, miniaturization of a heat exchanger is calculated | required with the downsizing of an air conditioner. For this reason, the heat exchange tube 106 also needs to use the heat exchange tube 106 of a diameter smaller than before.

However, when the expansion apparatus 200 shown in FIG. 6 expands into the heat exchange tube 106 of a narrower diameter than before, and the flare part was formed in the opening part which expanded, the straight pipe of the heat exchange tube 106 is carried out. It has been found that a buckling phenomenon tends to occur at or near the boundary between the portion 106a and the hairpin portion 106b.

Therefore, in the present invention, when the tube is expanded to a U-shaped heat exchange tube having a smaller diameter than before, and a flare portion is formed in the expanded tube, the buckling phenomenon is at or near the boundary between the straight tube portion and the hairpin portion of the heat exchange tube. Even if the problem of the conventional heat exchange tube expansion method and the heat exchange tube expansion device which is easy to generate | occur | produce is eliminated, even if it expands into the U-shaped heat exchange tube of a narrow diameter than before, a flare part may be formed in the opening part which expanded. The present invention provides a method for expanding a heat exchange tube and a device for expanding a heat exchange tube in which buckling and the like do not occur.

MEANS TO SOLVE THE PROBLEM The present inventors examined in order to solve the said subject, and when the expansion billet inserted into the U-shaped heat exchange tube reached the boundary of or near the straight pipe | tube part of a heat exchange tube, and the vicinity, when the primary expansion completed, The billet is maintained at the position where the primary expansion is completed, and a flare is formed by inserting a flare punch in the opening of the heat exchange tube subjected to the primary expansion, thereby expanding the expansion of the U-shaped heat exchange tube having a smaller diameter than before. Even when a flare part was formed in the opening part of a heat exchange tube, it turned out that generation | occurrence | production of buckling etc. can be prevented.

That is, as a means of solving the said subject, as a expansion method of a heat exchange tube, a U-shaped heat exchange tube is inserted in each of the some insertion hole formed in each fin of the fin layer which laminated | stacked several sheets, and each heat exchanger is carried out. Projecting the opening of the tube from the top surface of the fin layer, and projecting the hairpin portion of each heat exchange tube from the bottom surface of the fin layer; Each expansion billet is inserted into each heat exchange tube by inserting an expansion pipe billet into each opening of the heat exchange tube to extend the diameter of each straight pipe of each heat exchange tube to perform primary expansion to integrate the heat exchange tube and the fin. Terminating the primary expansion in a state of being inserted at or near the boundary between the straight tube portion and the hairpin portion; Maintaining the expansion billet at the position where the primary expansion pipe ends, and inserting a flare punch into the opening of the heat exchange tube subjected to the primary expansion pipe to form a flare at the tip of the heat exchange tube. We can suggest expansion method of.

Moreover, as a means to solve the said subject, As a heat exchange tube expansion apparatus, The press-fitting plate provided with the rear end part of the several mandrel by which expansion pipe billet was attached to the front-end part, and was able to be elevated up and down by the drive means; An opening of a U-shaped heat exchange tube which is suspended by the hanging member on the press-fitting plate and is inserted into each of a plurality of insertion holes formed in each pin of the pin layer in which a plurality of fins are stacked and protrudes from an upper surface of the pin layer. A flare stand on which flare punches are formed which form flares; And a balancer provided below the flare stand and in contact with the flare stand that has been lowered together with the press-fitted plate that drives and lowers the driving means to support the flare stand at a predetermined position. The means is provided with the expansion billet for performing primary expansion to lower the press-fitting plate, expand the straight pipe portion of the heat exchange tube, and integrate the heat exchange tube with the fin while the flare stand is supported at the predetermined position by the balancer. When reaching the boundary of or near the straight pipe portion and the hairpin portion of the heat exchange tube and the primary expansion is completed, the drop of the press-fitting plate is adjusted to stop at the position not to press the flare band, and the expansion device of the heat exchange tube When the drop of the press-fitting plate stops, the expansion billet is held at the position where the primary expansion is completed, It is possible to provide a heat exchange tube expansion apparatus further comprising a lowering means operable to lower the flare on which the flare punch is mounted so as to form a flare at the tip of the heat exchange tube where the primary expansion is completed.

In general, in the U-shaped heat exchange tube, the hairpin portion subjected to the bending process is harder than the straight pipe portion without any processing by work hardening by bending process.

In the conventional expansion method, when the expansion billet reaches a predetermined position of the straight pipe portion of the heat exchange tube, the expansion billet and the flare punch are simultaneously pressed. For this reason, the stress by the expansion billet and the flare punch are simultaneously applied to the boundary between the straight tube portion and the hairpin portion of the heat exchange tube and the vicinity thereof.

It is considered that such a stress cannot be tolerated in a heat exchanger tube having a smaller diameter than conventionally, and buckling or the like is likely to occur.

In this regard, in the expansion method and expansion device provided by the present inventors, when the flare portion is formed in the opening of the heat exchanging tube subjected to the primary expansion, the expansion billet is held at the position where the primary expansion is completed, and the flare punch is performed. Only the bay is inserted into the opening of the heat exchange tube. For this reason, only the stress by a flare punch is applied to the boundary of the straight pipe | tube part of a heat exchange tube, and vicinity.

In addition, at that time, the expansion billet located at or near the boundary between the straight tube portion and the hairpin portion of the heat exchange tube is reinforcing the boundary at or near the straight tube portion and the hairpin portion of the heat exchange tube.

As described above, in the expansion method and the expansion device provided by the present inventors, when the flare portion is formed in the opening of the heat exchanging tube subjected to the primary expansion, the boundary or the vicinity of the straight pipe portion and the hairpin portion of the heat exchange tube is reinforced by the expansion billet. At the same time, only the flare punch is inserted into the opening of the heat exchange tube.

As a result, the stress applied to the boundary of or near the straight tube portion and the hairpin portion of the heat exchange tube reinforced by the expansion pipe billet can be reduced, and expansion can be carried out without causing buckling to the heat exchange tube having a smaller diameter than conventionally. .

1A and 1B are front and side views showing an example of the expansion device provided by the present inventors.
2A and 2B are front and partial cross-sectional front views illustrating an example of the flare punch used in the expansion pipe shown in FIG. 1.
It is a front view explaining the adjustment stand installed in the expansion device shown in FIG.
4A and 4B are explanatory views for explaining a method for expanding a heat exchange tube using the expansion device shown in FIG. 1.
5A and 5B are explanatory views for explaining a conventional expansion method.
6 is a front view illustrating a conventional expansion device.
7A and 7B are explanatory views for explaining the expansion method using the expansion device shown in FIG. 6.

(Form to carry out invention)

An example of the expansion apparatus of the heat exchange tube which this inventor provides is shown in FIG. As shown in FIG. 1A, the expansion pipe shown in FIG. 1 is equipped with rear ends of a plurality of mandrels, in which expansion pipes are mounted on the front end thereof, and are provided so as to be movable up and down by a cylinder device 10 as a driving means. It is provided below the flare stand 16, the flare stand 16 suspended by the press-fitting plate 12, the hanging members 14, 14, ... on the press-fit plate 12, and is shown in FIG. 1B. As described above, the balancers 18 and 18 which contact the flare stand 16 which has descended together with the press-fitting plate 12 which drives and descends the cylinder device 10 and support the flare stand 16 at a predetermined position are provided. Is installed.

This flare stand 16 is equipped with a flare punch shown in Fig. 2 in which expansion pipe billets are inserted and inserted into openings of U-shaped heat exchange tubes subjected to primary expansion pipes to form flares.

The flare punch 24 shown in FIG. 2 is a hollow body in which the through-hole 25 was formed along the center axis | shaft, as shown to FIG. 2B. As shown in FIG. 2A, the mandrel 20 in which the expansion pipe billet 22 is attached to the front end portion is inserted into this through hole 25. As shown in FIG.

At the distal end of the main body portion 26 of the flare punch 24, a guide portion 32 formed at the same outer diameter as the maximum outer diameter W of the expansion pipe 22 is formed. On the rear end side of the guide portion 32, a tapered shape is formed between the secondary expansion pipe portion 28 having a larger diameter than the guide portion 32 and the main body portion 26 having a larger diameter than the secondary expansion pipe 28. Flare forming portion 30 is formed.

In addition, by making the length of the guide part 32 substantially the same as the secondary expansion pipe | tube 28, correction of the inclination of the heat exchanger tube primaryly piped, etc. can be performed easily.

The adjusters 36 and 36 are movable at predetermined positions of the screw rods 34 and 34 as the support body extending upward from the flare stand 16 on which the plurality of flare punches 24 and 24 shown in FIG. 2 are mounted. Is installed.

The position of these adjustment tables 36 and 36 is a position where the press-fitting plate 12 which dropped by the drive of the cylinder apparatus 10 stops, and is the position where the primary expansion pipe | tube of a heat exchange tube is complete | finished.

3, cylinder apparatuses 38 and 38 as pressing means are provided in the moving part 36a which meshes with the screw rod 34 and can be positioned in the up-down direction as shown in FIG. The plate plate 36b which abuts against the press-fitting plate 12 which stopped descent | hung is attached to the upper end surface of the rod 38a, 38a of such cylinder apparatus 38, 38. As shown in FIG.

When these cylinder apparatuses 38 and 38 are driven, the press-fitting plate 12 whose drop has stopped is pushed upward through the plate plate 36b.

In this way, when the cylinder devices 38 and 38 are driven, the pressure for pressing the press-fitting plate 12 upwards resists the flare 16 against the balancers 18 and 18 via the screw rods 34 and 34. It acts as a descent force to dive. For this reason, the cylinder apparatuses 38 and 38, the plate board 36b, and the screw rods 34 and 34 comprise the descending means which lowers the flare 16. As shown in FIG.

In addition, the adjustment table 36 shown in FIG. 1A is seen from the direction of arrow A shown in FIG.

Using the expansion apparatus shown in FIG. 1, as shown in FIG. 4, with the several collar formed in each pin 50 of the pin layer 54 which laminated | stacked several pin 50, 50, ... When the U-shaped heat exchange tube 56 is inserted into each of the holes 52, 52,... And the pipe is expanded to the heat exchange tube 56 passing through the fin layer 54, the expansion apparatus shown in FIG. 1 is shown. Below the flare stand 16, the fin layer 54 into which the some heat exchange tube 56 was inserted is set.

At that time, as shown in FIG. 1, the hairpin part 56b which protrudes from the lower end surface of the pin layer 54 is inserted in the U-shaped groove 58a formed in the receiving part 58 provided in the expansion device.

The cylinder device 10 is driven to each opening part of the heat exchange tubes 56, 56, ... which made the hairpin part 56b insert into the U-shaped groove | channel 58a of the receiving part 58, and was installed. Then, the press fitting plate 12 is lowered, and as shown in FIG. 4A, an expansion pipe billet 22 provided at each tip of the plurality of mandrels 20 and 20 equipped with rear ends is inserted into the press fitting plate 12. By the insertion of the expansion billet 22, the heat exchange tube 56 is subjected to primary expansion in which the straight pipe portion 56a is expanded and integrated with the fin 50.

At the start of such primary expansion, the flare stand 16 also falls until it comes into contact with the balancers 18 and 18 in accordance with the drop of the press-fitting plate 12. This flare stand 16 is provided with a plurality of flare punches 24, 24,... Shown in FIG. 2, and when the flare stand 16 contacts the balancers 18, 18, FIG. 4A. As shown, the tip of the flare punch 24 is located at or near the opening of the heat exchange tube 56.

In addition, the press-fitting plate 12 is lowered, and the expansion pipe billet 22 performs primary expansion of the straight pipe portion 56a of the heat exchange tube 56. In this primary expansion, the flare 16 is held at a predetermined position by the balancers 18 and 18. For this reason, the flare punch 24 attached to the flare stand 16 is maintaining the state located in the opening part of the heat exchange tube 56, or its vicinity, as shown to FIG. 4A.

Subsequently, when the expansion billet 22 reaches the boundary between or near the straight pipe part 56a and the hairpin part 56b of the heat exchange tube 56 as shown in FIG. 4A, and the primary expansion is completed, The cylinder apparatus 10 is adjusted so that the fall of the press-fitting plate 12 may stop.

When the dropping of the press-fitting plate 12 stopped, the four cylinder devices 38 provided in the control panels 36 and 36 positioned at the position were simultaneously driven to drive the press-fitting plate 12 to the plate plate ( Press upward through 36b). The force pushing the indentation plate 12 of the cylinder device 38 upwards acts as a dropping force on the flare 16 through the threaded rods 34 and 34.

The total pressing force of the four cylinder devices 38 provided in these adjustment boards 36 and 36 is adjusted so that it may become larger than the pressure of the balancers 18 and 18 which support the flare base 16. As shown in FIG. For this reason, the flare base 16 falls independently by resisting the force of the balancer 18,18.

Therefore, as shown in FIG. 4B, the expansion pipe billet 22 attached to the press-fitting plate 12 via the mandrel 20 is connected to the straight pipe portion 16a of the heat exchange tube 56 where the primary expansion pipe is completed. The tip portion of the flare punch 24 mounted on the flare stand 16 is inserted into the opening of the heat exchange tube 56 while maintaining at or near the hairpin portion 16b.

When the front end of the flare punch 24 is inserted into the opening of the heat exchange tube 56, the guide portion 32 corrects the heat exchange tube 56 in which primary expansion is performed to incline and the like. The central axis of 56 coincides with the central axis of flare punch 24.

Subsequently, the secondary expansion pipe portion 28 of the flare punch 24 is inserted into the opening of the heat exchange tube 56, and secondary expansion is performed at the tip end of the heat exchange tube 56 and its vicinity, and primary expansion is performed. The diameter expansion part 59 of larger diameter than the one heat exchange tube 56 is formed.

In addition, the flare portion 60 is formed at the tip of the diameter expansion portion 59 by the flare forming portion 30 of the flare punch 24.

Thus, by inserting the front end of the flare punch 24, the 2nd expansion pipe | tube and the 3rd expansion pipe | tube are given to the heat exchange tube 56 which performed the primary expansion pipe | tube, and the diameter expansion part 59 and the flare part 60 are carried out. When forming the pipe, the expansion billet 22 is held at or near the boundary between the straight pipe portion 56a and the hairpin portion 56b of the heat exchanging tube 56 where the primary expansion is completed, and the tip end of the flare punch 24 is formed. Is inserted into the opening of the heat exchange tube 56. For this reason, the diameter expansion part 59 and the flare part 60 by the insertion of the front-end | tip part of the flare punch 24 in the boundary of or near the straight pipe part 56a of the heat exchange tube 56, and the hairpin part 56b. Only stresses that form

Therefore, in the expansion method shown in FIG. 4, in the expansion method in the conventional expansion method shown in FIG. 7, the stress which is received in the boundary between or near the straight pipe part 56a of the heat exchange tube 56, and the hairpin part 56b is shown. It can be made small compared with the case where the stress of the primary expansion pipe | tube by the billet 108 and the stress which forms the flare 114 by the flare punch 24 are received.

In addition, in the expansion method shown in FIG. 4, when the flare portion 60 is formed by the insertion of the tip portion of the flare punch 24, the straight pipe portion 56a of the heat exchange tube 56 and the hairpin portion 56b are formed. As a result of the reinforcement of the boundary or the vicinity of the expansion billet 22, even when a heat exchanger tube having a diameter of 6.5 mm or less is used, the straight tube portion of the heat exchange tube 56 is formed at the time of formation of the flare portion 60. Buckling at or near the boundary between 56a) and the hairpin portion 56b can be prevented.

In this way, the expansion of the heat exchange tube 56 is completed, the cylinder device 10 is driven to raise the press-fitting plate 12, and the heat exchange tubes 56 and 56 have a fin layer in which the fins 50 and 50 are integrated. 54) is removed from the expansion device.

In the above description, although the flare punch 24 in which the guide part 32, the secondary expansion part 28, and the flare forming part 30 were formed one by one from the front-end | tip of the main body part 26 is used, the secondary expansion part ( 28) and the flare punch in which only the flare forming part 30 is formed may be used, and the flare punch in which only the flare forming part 30 is formed may be used.

Claims (16)

In the expansion method of the heat exchange tube,
A U-shaped heat exchange tube is inserted into each of the plurality of insertion holes formed in each fin of the fin layer in which a plurality of fins are stacked to protrude the opening of each heat exchange tube from the upper surface of the fin layer, Protruding the hairpin portion of the heat exchange tube from the bottom surface of the fin layer;
Each expansion billet is inserted into each heat exchange tube by inserting an expansion pipe billet into each opening of the heat exchange tube to extend the diameter of each straight pipe of each heat exchange tube to perform primary expansion to integrate the heat exchange tube and the fin. Terminating the primary expansion in a state of being inserted at or near the boundary between the straight tube portion and the hairpin portion;
And maintaining the expansion billet at the position where the primary expansion pipe ends, and inserting a flare punch into an opening of the heat exchange tube subjected to the primary expansion pipe to form a flare at the tip of the heat exchange tube. Expansion method of heat exchange tube made into. The method of claim 1, wherein as each flare punch,
A secondary expansion unit for performing secondary expansion to further expand the diameter of the distal end of or near the heat exchange tube subjected to the primary expansion;
A flare forming portion formed at a rear end side of the secondary expanding pipe portion and inserted into a distal end of the heat exchanging tube subjected to the secondary expanding pipe to form a flare portion; And
The heat exchanger is formed on the tip side of the secondary expansion pipe portion and inserted into the heat exchange tube when the flare portion is formed at the tip end of the heat exchange tube so that the center axis of the heat exchange tube and the center axis of the flare punch coincide with each other. And a flare punch provided with a guide portion for positioning the tube. 3. The method for expanding a heat exchange tube according to claim 2, wherein the outer diameter of the guide portion is set to the same diameter as the maximum outer diameter of the expansion billet. 4. The flare punch according to any one of claims 1 to 3, wherein the flare punch is positioned at or near the tip of the heat exchange tube when the expansion billet is inserted into the heat exchange tube to initiate primary expansion. Expanding the heat exchange tube, characterized in that for adjusting the position. The heat exchange tube expansion method according to claim 1, wherein a heat exchange tube having an internal diameter of 6.5 mm or less is used as the heat exchange tube. The heat exchange tube expansion method according to claim 2, wherein a heat exchange tube having an internal diameter of 6.5 mm or less is used as the heat exchange tube. The heat exchange tube expansion method according to claim 3, wherein a heat exchange tube having an internal diameter of 6.5 mm or less is used as the heat exchange tube. The heat exchange tube expansion method according to claim 4, wherein a heat exchange tube having an internal diameter of 6.5 mm or less is used as the heat exchange tube. In the expansion device of the heat exchange tube,
A press-fitting plate having a rear end portion of a plurality of mandrels having expansion pipe billets mounted on the front end thereof, the press-fitting plate being provided to be moved up and down by a driving means;
An opening of a U-shaped heat exchange tube which is suspended by the hanging member on the press-fitting plate and is inserted into each of a plurality of insertion holes formed in each pin of the pin layer in which a plurality of fins are stacked and protrudes from an upper surface of the pin layer. A flare stand on which flare punches are formed which form flares;
And a balancer provided below the flare stand and in contact with the flare stand that has been dropped with the press-fitting plate driving and driving the drive means to support the flare stand at a predetermined position.
The driving means of the press-fitting plate has a primary expansion pipe for lowering the press-fitting plate, expanding the straight pipe portion of the heat-exchanging tube, and integrating the heat-exchanging tube with the fin while the flare stand is supported by the balancer at a predetermined position. When the expansion billet reaches the boundary of or near the straight pipe portion and the hairpin portion of the heat exchange tube, and the primary expansion is completed, the drop of the indentation plate is adjusted to stop at the position not to press the flare stand,
The expansion device for the heat exchange tube is such that when the drop of the press-fitting plate stops, the expansion billet is maintained at a position where the primary expansion pipe ends, and a flare is formed at the tip of the heat exchange tube where the primary expansion pipe is completed. And a lowering means operable to lower the flare stand on which the flare punch is mounted. 10. The method of claim 9, wherein the lowering means for lowering the flare zone is:
A support extending upward from the flare zone;
An adjusting table which is provided to be movable to the support, and which is positioned at or near the position where the drop of the indentation plate stops; And
And a pushing means provided on the adjusting table and pressing upwardly the press-fitting plate on which the dropping stops. 11. The method of claim 9 or 10, wherein each flare punch is:
A secondary expansion unit for performing secondary expansion to further expand the diameter of the distal end of or near the heat exchange tube subjected to the primary expansion;
A flare forming portion formed at a rear end side of the secondary expanding pipe portion and inserted into a distal end of the heat exchanging tube subjected to the secondary expanding pipe to form a flare portion; And
The heat exchanger is formed on the tip side of the secondary expansion pipe portion and inserted into the heat exchange tube when the flare portion is formed at the tip end of the heat exchange tube so that the center axis of the heat exchange tube and the center axis of the flare punch coincide with each other. And a guide part for positioning the tube. 12. The heat exchange tube expansion apparatus according to claim 11, wherein the outer diameter of the guide portion is the same diameter as the maximum outer diameter of the expansion billet. 10. The heat exchanger according to claim 9, wherein when the balancer is in contact with the flare stage, the balancer is positioned so that the tip of the flare punch provided on the flare stage is positioned at or near the opening of the heat exchange tube. Tube expansion device. The heat exchanger according to claim 10, wherein the balancer is positioned such that when the balancer is in contact with the flare stage, the tip of the flare punch provided on the flare stage is positioned at or near the opening of the heat exchange tube. Tube expansion device. 12. The heat exchanger according to claim 11, wherein when the balancer is in contact with the flare stage, the balancer is positioned such that the tip of the flare punch provided on the flare stage is positioned at or near the opening of the heat exchange tube. Tube expansion device. The heat exchanger according to claim 12, wherein when the balancer is in contact with the flare stage, the balancer is positioned such that the tip of the flare punch provided on the flare stage is positioned at or near the opening of the heat exchange tube. Tube expansion device.

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